Process for smelting and refining



Mmh 29,1949. I L. M. LONG v 2,465,893

PROCESS FOR SMELTING AND REFINING Filed July 7, 1947 gin 0W PatentedMar. 29, 1949 UNITED STATES PATENT OFFICE PROCESS FOR SMELTIN G ANDREFINING Leighton M. Long, Toledo, Ohio Application July 7, 1947, SerialNo. 759,344

1 Claim. 1

This invention relates to remelting metal practices, more particularlyin the establishment of alloy character or grading in the refining andsmelting as of non-ferrous metals, as from scrap or miscellaneoussources.

This invention has utility in the preparation or forming of sections oringots, with adaptability for ready handling and merchandising,including efficiency facilities for readily responding to definite andspecial formula or requirements in the ultimate use at foundryoperations in casting production.

Referring to th drawings:

Fig. 1 is a vertical section thru a mold with an ingot, under theinvention, therein;

Fig. 2 is a perspective View of a pig or ingot, say of brass or bronzein current practice as a foundry supply item;

Fig. 3 is a perspective view of an ingot under the invention herein, sayas produced from the mold of Fig. 1;

Fig. 4 is a side elevation of a crucible, with parts broken away,showing charge therein of applicants ingots, for remelting at a foundry;

Fig. 5 is a View on an enlarged scale, with portions broken away,showing a special adaptability of the ingot hereunder in a melt to bringdown the over-temperature from the melting heat to the range for thepour or casting, as well as incidental thereto, supply of a flux elementor elements, as may be required for oxidizing or deoxidizing, as theparticular situation may demand; and

Fig. 6 is a perspective view of a stack of ingots on a pallet.

The various substances in certain non-ferrous metal scrap of the generalbrasses and bronzes characteristics generally carry in varyingproportions copper, tin, lead and zinc, of the differing alloys orcompounds. Almost indiscriminately from heterogeneous sources, apractice current is to remelt into shallow open top molds in theproduction of pigs I, say in the range of 25#. Such a pig I at its smalldimension or bottom may run 2" x 5" and when 3" deep or high, have itstop or larger area face around 4 x 9". The top maximum side area exposesa large percentage of the metal body to oxidizing action of the air.Detrimental or less specific gavity inclusions rise to this surface asthe melt for the pig tends to solidify. To clear the pig I from such Illobjectionable mass, a practice has been to skim before fully congealed.More favor has been met thru supplying a coating of powdered charcoal.This latter course tends to leave less rough places or irregularities 2.The carbon coating does not contribute to attractive appearance of thepig -I, and the carbon may, to some extent, be incorporated in the pigand to such extent affect or modify the analysis and the character ofthe product to be had therefrom.

These undesirable and objectional experiences are avoided under theinvention herein. A multiple or single chamber mold may comprise a pairof sections 3, 4, relatively slidable into complementary registerrelation to form a mold chamber 5 having a relatively small area top 6.In carrying out the practice hereunder a cast or ingot T from a toppouring of a melt into the chamber 5 has its skum or impurities confinedwith the consequent almost total elimination of oxidation loss. Thesides and bottom of the chamber 5 may be at least upon a A. radiusedges, thereby avoiding sharp corners and occasion to wound the handlerthereof. With the ingot 1 formed for say 1 square, it may be gauged forlength, say for 20" for a saw off or cut 8 to sever a section 9 toinclude the scum and undesirable matter.

There is thus completed an article I9 as an ingot of definite shape,Weight and dimension. The ingot II] has four similar size and dimensionrectangular parallogram long sides H extending between a pair of muchless area square ends l2. These ingots I9 may be readily assembled intoa stable stack I3 on a pallet 14. In warehousing, storage and. generalhandling practices, quantity identification is readily and reliably setup, and a transfer truck may enter beneath a stack on a pallet i l andtake the stack l3 to and from storage.

When a crucible l5 has been prewarmed for a charge, the truck may bringthe stack l3 into a convenient position for the operator or foundrymanto take the ingots In from the stack l3 and insert the ingots on end inthe crucible l5. In practice, the ingots 40 for remelting may be chargedinto various types of furnaces, such as reverberatory, and with theopening for receiving the charge as at a side or bottom. The ingots Itbeing of considerable length as to their crosssection, may hav an end l2thrust into the furnace opening, and as so directed, thrust sufliciently into the furnace to form a stack to be melted, or to become a partof a molten mass or pool. Considering the 25# pig I as having a surfacein the range of 100 sq. in., this would make the exposure or face around4 sq. in. per pound. In comparison the 20. ingot I has its surface rangeabout 150 sq. in., or around 7 /2 sq. in. per pound. By taking the pig Ito represent 100%, it is to b noted that there is 8'7 for the ingot I!)in its surface open to direct more heat attack. This is a direct heatefficiency advantage for the ingot I0, regardless of the character ofremelting operation or the furnace therefor, as well as of the manner ofplacing or introducing the ingot I a into such furnace. With the heat onat the furnace, any symmetrical stackine may not be convenientlypossible. That is, the throwing in of the ingots It may be sort ofhelter-skelter. Nevertheless, as introduced in a common or generaldirection, there is approximate parallelism in the usual grouping.

More specificaly, the crucible I5 may be taken as for say a 750#capacity of metal to be brought to the molten stage. With its availablespace approximating 3845 cu. in., a full charge into such hot crucibleI5 would be about 16 pigs I or 400#. The actual displacement would netabout 1250 cu. in. thereby leaving voids approaching 2600 cu. It is tobe noted that this leaves over two-thirds voids and not quite up to halfof the charge capacity for the crucible I5 to handle 7501i.

Notwithstanding the crucible I5 be hot, it is convenient and practicablefor the foundryman to thrust the ingots II) on end thru the open top ofthe crucible IE to rest on bottom I6 of the crucible. The fact is thatsome 37 ingots I0 may be placed in on-end grouping conveniently in thecrucible I5, thereby establishing a charge of 740# in bringing thecharged crucible into the working range of its full capacity of 750#.With this charge having a displacement of about 2300 cu. in. as against1250 cu. in. for the charge of the pigs I, there is 85% more metal inthe crucible I5 to be made molten. The Voids now run with the ingots I0and the charge of 31 into the crucible I5, to be under 1600 cu. in. asagainst 2600 cu. in. in the charge with the ingots I. The reduction inthe voids thus shows as upward of 70%.

In foundry practice, a factor of safety may be adopted as to thetemperature for the actual pouring into the molds for the castings to beproduced. For instance, the optimum fluidity of an alloy for a certaintype of casting operation may be 2150 F. In the handling of this job ofpouring, the foundryman may bring the melt in the crucible I5 to therange of 2250 F. There is thus available 100 F. for drop in getting themolten metal into the molds. Furthermore, there may be occasion forfinal doctoring, which, if for temperature only, may be by introducingan additional ingot I0. Should there be need for oxidizing ordeoxidizing, the ingot i0 may have an end pocket II for a flux capsuleI8, retained by a plug I9, and tongs 20 used to place the treating agentI8 at the bottom of the melt 2 I.

The relatively minor exposed-to-air portion of the ingot I in the mold3, l, normally requires quite an interval for cooling sufficiently thatthe set or congealed condition has developed shrinkage release so thatthe sections 3, 4, may be on side and slid apart to expose the ingot tohave the} dross 9- trimmed Off. With the sides of the squares for theends I2 of the ingot I0, under 2 as a maximum dimension, and thesymmetrical cross-section ingot I0 having its remote or opposite end inthe range of 20", there is multiple length dimension as to end or top.The polygon ends I2 have parallelogram sides upward of ten times longerthan wide. The relatively slender overall appearance of the ingot II]means that heat travel into the ingot is quite a little less than 1" asa maximum. It follows therefrom that the extensive proportional surfacearea is a very material factor in the speed of heating operation.Considering the area relatively to the total mass of the ingot, there isa saving of nearly half; i. e., per pound, about half the heat units arerequired to bring the ingot I0 up to fusion, thruout, as for the ingotI. Further efficiency in the foundry practice is made possible by thefact that at a single charge the crucible may be brought to capacity forthe melt. This avoids the course of less than capacity charge for thecrucible. In the event the operator using the pigs I should seek tobring the crucible charge up to capacity, there is the chill forintroducing the additional pigs I into the molten mass.

While the practically negligible air exposure top for the ingot I mayeliminate greatly if not entirely occasion for deoxidizing, should therebe need therefor, the counter-practice of oxidizing, or some specialalloy, fiuxing or other treatment, such may be nicely and effectivelyhandled, even without need for puddling or stirring, for by making therelease of the capsule or charge I8 deep down in the molten mass, theforthwith melting thereof tends automatically to effect generalpermeation and uniformity.

What is claimed and it is desired to secure by Letters Patent is:

The methodv of foundry practice comprising,

'1 materially contributing to heat, material and labor economy, thru theperformance in sequence of the steps of pouring a remelt of non-ferrousscrap metal into an open top mold to form an ingot blank with anair-exposed upper end area in the range of one tenth or less than a fiatside area of the blank length thereto, and with the blank approximatinguniform cross-section thruout said length, separating a deleteriousmatter upper section by end gaging the blank to leave a refinedhomogeneous body metal ingot, laterally supporting a plurality of saidingots against a rising side wall of a crucible, with the ends of saidingots resting on the bottom of the crucible,

placing additional of said ingots side-by-side,

with said plurality of ingots to the range of 75% of the crucible meltcapacity, fusing the cruciblecontained on-end ingots into a pool of adepth approximating 75% of the ingot length by simultaneously thruoutminor crosssection decreasing the extent upward of the plurality ofingots, carrying the fusion heating of the pool to a temperature inexcess of that for foundry pouring use thereof, partially utilizing theexcess temperature to melt off an oxidation-control-agentcarryingspecial end of an additional normal temperature similar length ingot bythrusting said end of the additional ingot to the vicinity of the bottomof the pool, and, after the melting off of the agent and continuouslytherefrom, bringingv the pool down to normal pouring temperature byfurther utilizing said excess temperature to melt the remainder of theadditional ingot into the. pool.

LEIGHTON M. LONG.

(References on following page) REFERENCES CITED The following referencesare of record in the file of this patent:

Number Newton et EL, Metallurgy of Copper, pub- 6 Name Date Pacz Aug.24, 1926 Merten Mar. 15, 1932 Whitmore Sept. 10, 1935 Jung Feb. 6, 1940Hughes July 29, 1941 Greenhow et a1. Aug. 12, 1941 Hulme et a1 Oct. 6,1942 Prucha Dec. 29, 1942 OTHER REFERENCES lishecl 1942 by John Wiley 8:Sons, Inc., London, Chapman and Hall, Limited, page 218.

